1. Technical Field
The present invention relates to an electronic control device for us in internal combustion engine for correcting control variables such as amount of fuel to be supplied or ignition timing of the internal combustion engine for vehicles in compliance with change in atmospheric pressure under a state of operating an exhaust gas recirculating apparatus.
2. Background Art
In the internal combustion engine for vehicles provided with exhaust gas recirculating (hereinafter simply referred to as EGR) apparatus, several control devices have been heretofore proposed for operating the internal combustion engine at a predetermined air/fuel ratio without being influenced by any change in atmospheric pressure. Control devices for changing control contents in compliance with change in atmospheric pressure to cope with the change in atmospheric pressure during running on a place of high altitude, etc. have been also provided. For example, the Japanese Patent Publication (examined) No. 89682/1994 discloses one of such control devices. In the prior art disclosed in this publication, a recirculation passage of EGR apparatus is subject to opening and closing. A first correction with respect to fundamental amount of fuel to be supplied is made on the basis of a difference in pressure between atmospheric pressure and intake pressure as well as an engine speed of the internal combustion engine under the state of opening the recirculation passage. In this first correction, amount of fuel to be supplied is increased in proportion to the difference in pressure. In case that atmospheric pressure becomes low irrespective of opening or closing the recirculation passage, second correction is made to increase the amount of fuel to be supplied. Thus, an object of this known art is to operate the internal combustion engine at all times at a predetermined air-fuel ratio in compliance with the change in atmospheric pressure.
Other than the foregoing prior art, the Japanese Patent Publication (examined) No. 2569586 proposed a further prior art. In this prior art, a first fundamental control value is calculated on the basis of intake pressure and engine speed of an internal combustion engine under the state of suspending operation of the EGR. A second fundamental control value under the state of operating the EGR is calculated on the basis of the first fundamental control value and a correcting value obtained from the intake pressure and the engine speed. The first and second fundamental control values are corrected by the correcting value obtained from another parameter of the internal combustion engine. Furthermore, in the calculation of the mentioned correcting value obtained from the intake pressure and the engine speed, the intake pressure is corrected by atmospheric pressure so that fuel system and ignition system are controlled by the calculated control value.
In case that amount of fuel injection, ignition timing and EGR valve opening in the internal combustion engine provided with the EGR apparatus are controlled merely by intake pipe pressure and engine speed of the internal combustion engine, atmospheric pressure changes when the running is shifted from a place of low altitude to that of high altitude. Back pressure also changes following the change in atmospheric pressure. Accordingly, even if valve opening of the EGR remains unchanged in the same intake pipe pressures and engine speed of the internal combustion engine, amount of introduction into the EGR changes. As a result, inconsistency occurs in the control of amount of fuel injection and ignition timing. That is, an air-fuel ratio to be controlled changes in case that amount of introduction into the EGR changes due to change in atmospheric pressure. Thus, there arises deterioration in exhaust emission and in drivability, and moreover knocking occurs due to deviation in required ignition timing.
In the mentioned prior arts, the Japanese Patent Publication (examined) No. 89682/1994 relates to the manner of controlling air-fuel ratio in conformity of change in atmospheric pressure. The Japanese Patent Publication (examined) No. 2569586 relates to the manner of changing control contents in the internal combustion engines in compliance with the change in atmospheric pressure. In both prior arts, intake pressure is corrected depending upon the atmospheric pressure, and the internal combustion engine is controlled according to the correcting value calculated from the corrected intake pressure and engine speed of the internal combustion engine. As a result, it cannot be always said that appropriate correction is made with respect to the internal combustion engine.
The present invention was made to solve the above-discussed problems and has an object of providing an electronic control device for internal combustion engine capable of controlling the internal combustion engine more stably in association with change in amount of EGR due to change in atmospheric pressure. The invention also provides a control method of internal combustion engine.
To accomplish the foregoing object, an electronic control device for an internal combustion engine according to the invention comprises:
atmospheric pressure detector means for detecting an atmospheric pressure;
operating condition detector means for detecting an operating condition of the internal combustion engine from engine speed and intake pressure of the internal combustion engine;
exhaust gas recirculation amount control means for controlling a recirculation amount of exhaust gas on the basis of a result detected by the mentioned operating condition detector means;
first fundamental control value calculating means for calculating a fundamental control value of the internal combustion engine on the basis of the result detected by the operating condition detector means in the suspended state of exhaust gas recirculation;
second fundamental control value calculating means for calculating a fundamental control value of the internal combustion engine on the basis of the result detected by the operating condition detector means in the operated state of exhaust gas recirculation;
control value calculating means for correcting a result calculated by the first fundamental control value calculating means or a result calculated by the second fundamental control value calculating means on the basis of a physical value representing a state of the internal combustion engine;
exhaust gas recirculation change calculating means for calculating a change in recirculation amount of exhaust gas at the time of change in atmospheric pressure in the form of a rate of change to the recirculation amount of exhaust gas under the standard atmospheric pressure on the basis of the result detected by the operating condition detector means and the result detected by the atmospheric pressure detector means in the operated state of exhaust gas recirculation; and
correction means for correcting the fundamental control value calculated by the second fundamental control value calculating means on the basis of the rate of change to the recirculation amount of exhaust gas calculated by the exhaust gas recirculation change value calculating means.
As a result of such construction, each control value of the internal combustion engine can comply with an actually required control value in case that atmospheric pressure changes at the time of implementing the control of the exhaust gas recirculation. Thus, an advantageous electronic control device for the internal combustion engine can be obtained.
In the electronic control device according to claim 2 of the invention, the fundamental control value is an amount of fuel injection of a fuel injection device.
As a result, the amount of fuel injection can comply with an actually required control value.
In the electronic control device according to claim 3 of the invention, the fundamental control value is a control value for ignition timing.
As a result, the ignition timing can comply with an actually required control value.
In the electronic control device according to claim 4 of the invention, the ratio of change of the recirculation amount of exhaust gas is calculated by the exhaust gas recirculation change calculating means as a function of atmospheric pressure and intake pressure.
As a result, the control values can precisely comply with an actually required control value of the internal combustion engine.
A method for controlling the internal combustion engine according to the invention in which an operating condition of an internal combustion engine is detected on the basis of engine speed of the internal combustion engine and intake pressure, a recirculation amount of exhaust gas is controlled on the basis of the detected result thereof, and a fundamental control value of the internal combustion engine is corrected in compliance with the mentioned operating condition;
the method comprising:
a step of calculating the fundamental control value of the mentioned internal combustion engine in compliance with the operating condition in the operated state of exhaust gas recirculation;
a step of calculating a change in recirculation amount of exhaust gas at the time of change in atmospheric pressure in the form of a rate of change thereof to the recirculation amount of exhaust gas under the standard atmospheric pressure in the operated state of exhaust gas recirculation; and
a step of correcting the mentioned fundamental control value on the basis of the mentioned rate of change.
As a result, it becomes possible to obtain an advantageous electronic control method for the internal combustion engine in which each control value of the internal combustion engine can comply with actually required control value in case that atmospheric pressure changes at the time of implementing the control of the exhaust gas recirculation.
In the mentioned step of calculating the fundamental control value, amount of fuel injection through a fuel injection device or an adjusting value of ignition timing is calculated as the fundamental control value.
As a result, it becomes possible to obtain the amount of fuel injection or of the ignition timing in compliance with the actually required value.